Senior businessmen at an all-male charity dinner groped and propositioned women hostesses who were told to wear “black sexy shoes” and black underwear, it has been claimed.

Undercover Financial Times reporters said they witnessed the behaviour at the annual President’s Club charity dinner in London’s Dorchester Hotel on Thursday night.

The black-tie event, attended by 360 figures from business, politics and finance, allegedly included auction lots involving a free lapdance at a Soho club and plastic surgery that could be used to “add spice to your wife”.

The FT reported that by midnight an unnamed “society figure” was telling a hostess “I want you to down that glass [of champagne], rip off your knickers and dance on that table.”

The FT alleged: “According to the accounts of multiple women working that night, groping and similar abuse was seen across many of the tables in the room.

“Hostesses reported men repeatedly putting hands up their skirts; one said an attendee had exposed his penis to her during the evening.”

The event was hosted by the comedian and children’s author David Walliams, who is not the subject of any allegations and is understood to have behaved correctly throughout the night.

It allegedly began with another male compere – not Walliams - telling the men “Welcome to the most un-PC event of the year”.

The event has now been condemned by MPs including the deputy leader of the Liberal Democrats, Jo Swinson who reacted to the allegations by saying the FT’s report showed that “a rotten, sexist culture is still alive and kicking in parts of the business community.”

The President’s Club charitable trust, which said the event raised millions of pounds for disadvantaged children, said it was “appalled by the allegations of bad behaviour” and pledged to investigate.

The FT said the 130 hostesses were hired by the agency Artista, which allegedly required that the women were “tall, thin and pretty”, and paid them £150 for the night, plus £25 for a taxi home.

The FT said that at their initial interviews, Caroline Dandridge, the founder of Artista, warned the women that the men at the dinner might be “annoying”.

Ms Dandridge was reported to have told one hostsess: “It’s a Marmite job. Some girls love it, and for other girls it’s the worst job of their life and they will never do it again. You just have to put up with the annoying men and if you can do that it’s fine.”

Two days before the dinner, Artista allegedly emailed the hostesses to say they should bring “black sexy shoes”, black underwear and do their hair and make-up in a style suitable for a “smart sexy place”.

At the event, Ms Dandridge is said to have briefed the women that if any of the men became “too annoying” they should tell her.

The FT reported that some men among the “mix of British and foreign businessmen, the odd lord, politicians, oligarchs, property tycoons, film producers, financiers, and chief executives” were holding hostesses’ hands as the starters arrived.

During the night a 28-year-old woman claimed to have been repeatedly fondled on the bottom, hips, stomach and legs, with one man inviting her upstairs to his hotel room.

The FT claimed that one 19-year-old woman was asked by a man in his seventies whether she was a prostitute.

She was reported to have said later: “I’ve never done this before, and I’m never doing it again. It’s f***ing scary.”

The Presidents Club told the FT: “The Presidents Club recently hosted its annual dinner, raising several million pounds for disadvantaged children.

“The organisers are appalled by the allegations of bad behaviour at the event asserted by the Financial Times reporters.

“Such behaviour is totally unacceptable. The allegations will be investigated fully and promptly and appropriate action taken.”

Ms Dandridge, of Artista, was quoted by the FT as responding to the allegations by saying: “This is a really important charity fundraising event that has been running for 33 years and raises huge amounts of money for disadvantaged and underprivileged children’s charities.

“There is a code of conduct that we follow, I am not aware of any reports of sexual harassment and with the calibre of guest, I would be astonished.”

When contacted by The Independent, a spokesman for Artista provided the same statement as that provided by the Presidents Club.

The Dorchester Hotel told the FT it had a zero-tolerance policy regarding harassment of guests or employees.

In a statement, the hotel said: “We are unaware of any allegations and should we be contacted we will work with the relevant authorities as necessary.”